(1) Previously disclosed art: My co-pending application which is incorporated and made a part hereof, discloses a system which, when manually propelled along a joint between wall panels, covers the joint with heat-sealable metallic tape heated by an electric soleplate of the system and which by means of locking the tape feed stops itself, preventing further propulsion, at exactly the right distance from a ceiling or floor, or other termination of the joint so that the tape, when plunger-cut using a provision of the system, will just extend to the ceiling or floor or other termination of the joint, and no more; for the purpose, the tape feed is locked by a sensor arm when the sensor arm strikes a ceiling or floor or other obstacle at the termination of the joint; a graduated adjustment provides for calibration of the system. An embodiment of the invention provides a special "V" shaped sole plate attachment which adapts it for applying heat sealing tape to joints between panels meeting at right angles, or 90.degree. joints, and that is the embodiment to which the present invention is directed.
(2) The improvement of the present invention: because the "V" bottom of the soleplate attachment is heated and should extend little, if any, beyond the edges of the tape to be heated, the width of the arms or flats of the "V" is necessarily limited. The relatively small "V" soleplate attachment may require some skill to keep in balanced or uniform contact with the two faces of the tape which is applied like a "V" trough in the 90.degree. joint, pressures into the "V" trough and along it being simultaneously required.
According to the present invention first and second adjustable contacts for guiding are disclosed to align with the soleplate attachment and stabilize it in the "V" trough, with the objects of providing greater aligning leverage and easier operation in an economical, efficient and light weight embodiment.